My mistake - I'm better on old names than current ones!
If it's Pelican Terrace, and I'm pretty sure it is, then it is definitely No 5. I've just spotted the drainpipe, which was in the middle of the terrace between 4 and 5.
According to local directories the Barlows lived there 1898/9 to 1916 - which would, I think, match pretty well with the post card back. I'd be more sure if Roger Vaughan's website hadn't gone massively awry recently so I shall have to seek an alternative photo back dating source!
It's a little odd that the directories all list A Barlow? Even odder the Lloyd George Domesday has Mark Ballard at No 5 in 1911/12. Just goes to show that directories are not the most accurate source!
You can see Pelican Terrace in this aerial view -
https://britainfromabove.org.uk/en/image/EPW059806/downloadAnd yes, the museum does have a photo (much later than yours) - a copy might be in the photo folders in their library. IIRC the library gave all their photos to the museum.